1. Field of the Invention
The present invention relates to a method for manufacturing an alumina sintered body and an alumina sintered body.
2. Description of the Related Art
To date, electrostatic chucks may be used when semiconductor wafers are subjected to surface treatments, e.g., film formation and etching. An electrostatic chuck in which an electrostatic electrode is buried in a disc-shaped alumina substrate and one surface of the alumina substrate serves as a wafer-mounting surface is known. An electrostatic force is generated between the electrostatic electrode and the semiconductor wafer by energizing the electrostatic electrode while the semiconductor wafer is mounted on the wafer-mounting surface of the electrostatic chuck. The semiconductor wafer is attracted and held by the wafer-mounting surface on the basis of the electrostatic force. Also, a heater electrode may be buried in the alumina substrate together with the electrostatic electrode. In this case, when the heater electrode is energized while the semiconductor wafer is mounted on the wafer-mounting surface, the semiconductor wafer is heated by the heater electrode. As for the method for manufacturing the alumina substrate used for such an electrostatic chuck, a method described in PTL 1 is known. According to PTL 1, initially, a slurry containing an alumina powder having a purity of 99.7%, a small amount of MgO raw material powder, a binder, water, and a dispersing agent is produced. Subsequently, the slurry is spray-dried, and the binder is removed at 500° C. so as to produce alumina granules. The resulting alumina granules are filled into a mold, and press forming is performed to produce a compact. The resulting compact is set into a carbon sheath and hot-press firing is performed so as to produce an alumina sintered body. The hot-press firing is performed by holding the compact in a nitrogen atmosphere (150 kPa) at 1,600° C. for 2 hours while a pressure of 100 kg/cm2 is applied, for example. The thus obtained alumina sintered body is subjected to grinding so as to produce the alumina substrate.